Defying the Darkness - Thermal Imaging Cameras

Thermal Imaging Cameras - Defying the Darkness

IP cameras, like the majority of cameras, need visible light in order to capture an image. Thermal Imaging cameras do not. They are able to function not only in total darkness, but under hostile conditions such as sand or dust storms as well

Although we tend to think of light in terms of what you see is what you get, visible light is but a fraction of the energy radiating in waves of varying lengths from the sun.  Since all light is energy traveling  at the same speed 186,000 miles per second, longer wavelengths occur at  lower frequencies, and conversely, shorter wavelengths occur at  higher frequencies. 

Visible light is that part of the electro-magnetic spectrum with wavelengths ranging from 400 to 700 nanometers. 

Infra-red light travels on longer wavelengths and lies just beyond visible light’s parameters

Since Thermal Imaging cameras utilize infra-red light, let’s examine it.

The Infra-red Portion of the Electro-Magnetic Spectrum

The prefix infra means below and is in the case of infra-red light means it occurs at a lower frequency than red light in the visible portion of the spectrum. Infra-red (IR) light can be divided into three categories:

1.       Near-infra-red.

The near in near-IR  signifies that it is the portion of the I-R spectrum closest to visible light with low

frequency wavelengths measuring from 700 – 1300 nanometers.

2.       Mid-infra-red

Mid-IR has lower frequency wavelengths of 1300 to 3,000 nanometers.

(Mid-IR and Near-IR near IR are used with a variety of electronic devices including remote controls.)

3.    Far infra-red (thermal) 

Far -IR occupies the largest part of the IR portion of the spectrum with wavelengths ranging from 3,000 Nano-meters to as long as 30,000 nanometers.  

The main difference between far IR and the other two is that near- and mid-IR are reflected off of objects while far-IR is emitted by them. Far-IR is also known as thermal-IR because this radiated energy gives off heat generated by activity at the atomic level of the object. This heat is key to thermal imaging technology.

How Thermal Imaging Works

All objects and beings give off some level of I-R radiation in the form of heat, or to put it another way, anything above the temperature of absolute zero (0 degrees Kelvin, or -469 degrees F) gives off measurable

I-R energy. While the amount of radiation emitted by you, me, a cat, dog, or a stone will differ, nothing radiates 100% of its temperature as I-R radiation.

Thermal imaging sensors work with emissivity, which is defined as the specific percentage of thermal radiation, to calculate an object’s true temperature in order to map out an image of the object within its environment.  At no time in the process is visible light required for thermal imaging.

How a Thermal Imaging Camera Works

Thermal imaging cameras contain a special lens that focuses the infra-red light emitted by everything in the field of view. Since there was be several thousands of points in the camera’s field of view, thermal cameras need special image sensors with a phased array of infra-red detector elements to gather them all together. Once the elements have captured the information they create a detailed temperature pattern known as a thermogram.

The thermogram is then translated into electric impulses that are sent to a signal-processing unit, then on to a

display where it appears as various colors depending on the intensity of the infra-red emission of each object. Taken together, these impulses create an image of the subject against its background.

Thermal Imaging to the Rescue

Thermal imaging technology is finding its way into the news more and more. Unfortunately, the news was not cheerful news. Responders made use of it during two very different tragedies.

 In Boston, the police used thermal imaging sensors to zero in on the surviving bomber in a residential neighborhood who was hiding in a covered boat dry-docked in a dark back yard.

Then in May, a two mile wide tornado cleared a twenty two mile swatch of Moore, Oklahoma, upending the majority of structures and leaving in their place teetering piles of rubble. Responders included the Oklahoma National Guard’s 146^th Airborne Support who used thermal imaging detectors to seek body heat under the five and six foot mounds of debris in an effort to locate possible trapped survivors.

Our sales engineers are known as the experts in IP cameras but Kintronics also has experience in designing thermal imaging cameras, numbering the U.S. Armed Forces among our customers. If you’d like to know more about thermal imaging or IP cameras www.kintronics.com or give us a call at 914-944-3425. You can also fill out an information request form and a sales engineer will respond promptly.